Fire dampers, as shown, for example, in my U.S. Pat. Nos. 3,273,632 and 3,401,734, are commonly mounted in inner walls and partitions and the like in buildings and are connected to the air duct work. In the prior art, the ordinary means for accomplishing this mounting and positioning was to place a sleeve about the fire damper, attach the sleeve to the fire damper frame, position the sleeve in the wall so that an outwardly extending flange of the sleeve abutted one surface of the wall; then position a separate piece of angle iron against the opposite face of the wall, and then bolt the sleeve to the angle iron. It was then necessary to provide a separate adapter means to attach the sleeve to the air duct work. In my prior art U.S. Pat. No. 3,727,663, I describe and claim an adapter means improvement on this prior art. Therein, the prior art just described is shown by the angle iron 20 attached to the sleeve in the upper left hand corner of FIG. 1a of the drawings. In the '663 Patent, the device comprises one or more sheet metal members co-extensive with a portion of the fire damper, which have been bent to engage the wall and the duct work.
In cases where the damper and sleeve are inserted through a wall and the other duct work is not in place, it is possible to go to the opposite side of the wall to place the angle iron in position and attach it to the sleeve as aforesaid. However, if the vertical portion of the duct work (known as a vertical chase) is in place, it is not possible to do that which has just been described and, accordingly, often dampers are merely placed in position on one side of the wall without attachment from the other side of the wall.
I have observed that masonry and dry wall construction is standardized in new construction in terms of their thickness. Thus, it is possible to predict the size of the depth of the frame of the fire damper within an acceptable degree of accuracy for purposes of mounting the fire damper.
I have also noted that the fire underwriters tests and actual fire conditions require that the fire damper be retained under the changing dynamic pressure conditions of a fire, so that the damper is not blown out of the wall. In other words, it is simply not enough to mount a damper, but the damper must be able to be retained within the wall during extreme pressure changing conditions. The present invention is directed to an apparatus and method for accomplishing that mounting in a simple and effective manner. Indeed, the present invention provides the only means of effectively mounting the damper from one side of a wall under conditions in which a vertical chase is already in place.